My copy of this book just came from Kinokuniya. I haven't had the chance to read it yet, only skim it, but for anyone out there who's dying of curiosity (I know I was) - as far as I can tell,

Spoiler (mouse over to view)

Firiel and Rune don't show up at all, they are only mentioned. The entire book is one long story that seems to be about Adale and a boy who looks like Rune (but has a totally different personality.) Although, this story may only be a story within a story, because in the first few pages, Adale is talking to Vincent, and Vincent addresses her as 'Evangeline', Adale's pen name, so I'm thinking this might be a story Adale tells Vincent - but I could be totally wrong. I apologize for this scattered info, I'm in a big hurry. When I have more time, I'll actually read the book and provide more conclusive info. I hope what I said was even a little helpful.